Axle Swap

I'm considering all the options to change my rear drum brakes to disk brakes on my 88 XJ (i.e. disk brake kits, adapting disk brakes, replacing the Dana 35 rear axle with a 93 Grand Cherokee Dana 35 rear that already has disk brakes on it). Since the 88XJ has leaf springs and the 93 Grand Cherokee has coil springs, will I have any interference problems with coil spring brackets or trailing arm brackets, etc? Do I have to remove/burn-off any brackets to make this swap work? I know I'll have to slightly modify the e-brake connection to make my e-brake work with the 93 rear end.

Thanks in advance!

Best regards,

CJR

swap a d35 for another d35? cant you just swap the brakes?

what size tires are you running?

the biggest problems with brakes on the 88 is the single diaphram brake booster. until you change that, the brakes will still suck, even with disks in the back.

i swapped in a booster and master from a 2000 grand for $80 and my 89 with 31's stop on a dime. as long as you give the rear drums some tender loving care, they should be fine, unless your running 35" tires.

From MadXJ....

http://www.madxj.com/MADXJ/technical/technicalfiles/BAzjRearDiscsOnXJ/ZJrearDiscsOnXJ.htm

There's a reason you dont want to use pre-1995 ZJ stuff, but I cant remember why....

89XJ

I've been trying to just get disk brakes off a Grand Cherokee and adapt them to my 88XJ. So far I haven't been successful. Then I found this 93 Grand Cherokee axle, but the junk yard only wants to sell the whole axle/disk brakes to me. If I can get the price down, then maybe this is an option.

JNickel101

I have a copy of that article and would like to do it if I could just buy the disk brakes instead of a whole axle w/disk brakes.

Best regards,

CJR

Sounds like that JY knows what a piece of crap the axle is, especially without the disc brakes attached to it....

I have 2 complete sets of ZJ D35 disk brakes for sale, PM me for details.

why disc brakes?

the real problem with the brakes on the 88 is the brake booster.

what size tire are you trying to stop.

89XJ,

To answer your question. My brakes never seem to hold their setting, no matter how many times I back-up to adjust them. I've checked the adjusters many times, replaced parts etc., and nothing changes. I'm running regular street times (235x75s) so tire size doesn't appear to be the problem.

Best regards,

CJR

Drums < Discs.

That should be good enough of a reason.

The ZJ c-clip D35 brake bolting pattern will be different than the non-clip Dana 35. You'll also be swapping in a weaker c-clip axle. Mid 90's Crown Vic brakes have the same bolt pattern as the non-clip D35 and are a pretty easy swap with a few minor mods (use a dremel to open up the center of the rotors a few thou and make a shim for the bearing retainer). Do a search and you'll find plenty of info. Probably even a few posts from me as I'm running 95 Crown Vic disks in the rear.

Blaine B. said:

Drums < Discs.

That should be good enough of a reason.

Click to expand...

depends how you look at it.

they require more maintenance and there are more parts. as for stopping, it depends on the setup.

the brakes on my 89 completely sucked. i looked into doing the rear disc swap. the problem is, unless the booster and master are replaced with a dual diaghram booster, the disc wernt going to be any better than the drums and the front brake issue has not been addressed. on my 89, both front and back brakes were horrible. basically the brake system was the problem.

so i did the booster and master swap with the intent of swapping out the drums if i needed to. after the first test drive i found out that there was no need for the disc conversion in the back.

i am 100% possitive that my 89 with 31" tires has better braking with 10"drums and the booster swap than it would have with just a disc swap.

Lawsoncl,

You state the ZJ bolt pattern(C-clip) is different than the 88XJ (non C-clip). I have Bill Ansell's article on adapting ZJ disc brakes to a 87 Dana 44 axle which he says is identical to a Dana 35(non C-clip). The ZJ backing plate bolt pattern was different and required redrilling, but he just dropped the rotors on the Dana 35(non C-clip) axle shafts without mentioning any redrilling of the bolt pattern on the rotors. His photos appear to show unmodified rotors. What am I missing here?

Best regards,

CJR

anybody have a link to an article outlining the brake booster swap? Seems that this is what my 1990 needs. Also running LT235's, braking is definately a bit weak for my liking, can't imagine what it would be like when I swap to 31's.

CJR said:

Lawsoncl,

You state the ZJ bolt pattern(C-clip) is different than the 88XJ (non C-clip). I have Bill Ansell's article on adapting ZJ disc brakes to a 87 Dana 44 axle which he says is identical to a Dana 35(non C-clip). The ZJ backing plate bolt pattern was different and required redrilling, but he just dropped the rotors on the Dana 35(non C-clip) axle shafts without mentioning any redrilling of the bolt pattern on the rotors. His photos appear to show unmodified rotors. What am I missing here?

Best regards,

CJR

Click to expand...

This article right?
http://www.madxj.com/MADXJ/technical/technicalfiles/BAzjRearDiscsOnXJ/ZJrearDiscsOnXJ.htm

I was talking about the bolting pattern on the end of the axle tube, not the wheel lug pattern.

The XJ D44, XJ D35 non-clip, and Ford Crown Vic share the same backing plate bolt pattern, which is different than the D35 c-clip pattern. Putting ZJ brakes onto the others requires either redrilling the end of the axle tube or redrilling the mounting plates to match. His article mentions redrilling the bottom two holes and welding up the original holes. He also had to bore our the center of the ZJs backing plates as the D44 bearing and retainer are larger.

All the rotors have the same 5x4.5" bolt pattern, so there is no need to redrill the rotors. When I swapped Crown Vic brakes onto my non-clip D35, I had to open up the center hub hole in the rotors a bit to get them to slide over the raised center on the axle shafts. I also had to enlarged the rotors bolt holes to get them to fully seat onto the D35 shafts. The amount was maybe 5 thousands and took 5 minutes with a die grinder and a sanding wheel.

With all that said, it's probably easier to transplant Crown Vic disks onto a D44 since you don't have to modify the backing plates. I think the stock D44 bearing retainer plate will also work just fine. You still have to adapt the brake hydraulic lines and parking brake connection, but you have to do something with them anyway.

Lawsoncl,

Re: The Ford Crown Victoria rear disc brake swap onto a 88XJ. In the article I read on it; it's mentioned that the driver's side caliper is mounted facing the rear, whereas on the passenger's side the caliper is mounted facing the front of the car. Why is that? Is this the way their mounted on the Ford Crown Victoria or is this the way it has to be mounted on a Jeep because of interference problems?

Best regards,

CJR

Not sure why Ford did it that way, other than it makes the parts identical on either side. If you want to flip things, you'd have to redrill and rotate the backing plate 180*. That would flip the e-brake lever to the top and make bleeding the caliper a pain as the bleeder would be on the wrong side.